In general, a DC relay or a magnetic switch, a sort of an electric circuit switchgear transmitting a mechanical driving force and a current signal using a principle of an electromagnet, is installed in various industrial facilities, machines, vehicles, and the like.
In particular, electric vehicles such as hybrid vehicles, fuel cell vehicles, golf carts, and electronic forklifts, and the like have an electric vehicle relay for supplying power of a battery to a power generating device and an electric device part or cutting off power supply thereto, and the electric vehicle relay is one of key components in electric vehicles.
FIGS. 1 and 2 are vertical cross-sectional views of a related art DC relay. FIG. 1 illustrates a breaking state (OFF state) and FIG. 2 is a conducted state (ON state).
A configuration of the related art DC relay includes a fixed contact 2 fixed to and installed on an upper portion of an arc chamber 1, a movable contact 3 installed to be linearly movable within the arc chamber 1 so as to be brought into contact with or separated from the fixed contact 2, an actuator A installed below the arc chamber 1 and linearly operating the movable contact 3, and a contact spring 4 for securing contact force of the movable contact 3.
The actuator A includes a coil 5 generating a magnetic field when external power is input, a fixed core 6 fixed to and installed within the coil 5, a movable core 7 installed to make a linear movement below the fixed core 6, a shaft 8 fixedly coupled to the movable core 7 and slidably coupled to the movable contact 3 in an upper end thereof, and a return spring 9 installed between the fixed core 6 and the movable core 7 and returning the movable core 7 in a direction away from the fixed core 6. Here, the shaft 8 is guided to be slidably movable through a shaft hole formed in a central portion of the fixed core 6.
An operation of the related art DC relay is as follows. First, an ON operation of the related art DC relay is as follows. When a current flows to the coil 5 during a breaking state, a magnetic field is formed around the coil 5 and the fixed core 6 is magnetized in the magnetic field. The movable core 7, compressing the return spring 9, is lifted by a magnetic attractive force of the fixed core 6. In addition, as the shaft 8 coupled to the movable core 7, while compressing the contact spring 4, is lifted to push up the movable contact 3 to contact the fixed contact 2, whereby a main circuit is conducted. That is, the DC relay is conducted.
Here, as the movable core 7 and the fixed core 6 collide, noise is generated.
Thus, emotional quality is degraded due to noise generated as the movable core 7 and the fixed core 6 collide during the ON operation.